1 Field of the Invention
The present invention relates to an information processing apparatus and method in which an input point or a trace of consecutive input points of a coordinate pointer is displayed or erased by moving the coordinate pointer on the surface of an input plate.
2 Related Background Art
A conventional information processing apparatus of the type that an input point or a trace of consecutive input points of a coordinate pointer is displayed or erased by moving the coordinate pointer on the surface of an input plate, is mainly constituted by a pen or mouse as the coordinate pointer, a liquid crystal display (LCD) or the like as a display unit integrally formed with the input plate on the surface of which the coordinate pointer is moved, and various controllers and drivers.
For example, as coordinate input systems having a coordinate pointer and an input screen, there are a resistor film system (pressure sensitive system), an ultrasonic wave using system, an electrostatic capacitance coupling system, an electromagnetic induction system, and the like.
With the information processing apparatus constructed as above, when an operator moves a coordinate pointer such as a pen near to the input screen, or touches the input screen with the coordinate pointer, the input point of the pen is detected by a controller, and in accordance with an output from the controller, a control means executes a predetermined function, e.g., a menu command execution. An input point of the pen is displayed by a driver circuit on the input screen, or a group of consecutive input points detected by a predetermined sampling is interconnected by a line to form the trace of the pen on the input screen. In addition, through recognition of this trace, characters or figures can be recognized, a gesture command can be executed, or other operations can be performed.
Input information of a pen for selecting an erasure mode of a menu command or an icon displayed on the input plate is also used as erasure information for instructing to erase (or temporarily erase) an already displayed point or line. In this case, the control means sets a predetermined size of a circle or rectangle area to be erased by one input point. A plurality of erasure area sizes are sometimes arranged to be set. Or in some cases, a point, line, or area is designated and erased by selecting an erasure command.
Such an information processing apparatus has various sizes ranging from a small portable size allowing a user to carry the apparatus in a suitcase or the like to a large size of a so-called electronic blackboard size. Since such an information processing apparatus can be used with a pen, like writing on a paper sheet, it provides easy-to-use man-machine interface.
However, with a conventional information processing apparatus, it is necessary for a user to rub the erasure area (points, lines, characters or figures made of points and lines) several times with a coordinate pointer such as a pen, if input information of the coordinate pointer is used as erasure information.
For example, if the erasure area set to one input point is small, the user is forced to rub the erasure area several times for a long time period with a pen or the like.
If a plurality of erasure area sizes for one input point are prepared, a suitable size is selected as large as possible. However, it is difficult to select a suitable erasure area size because of a difference between the erasure area size and the size of a coordinate pointer (e.g., a pen having a needle-like tip considerably smaller than an erasure area of points or lines). Therefore, when touching the erasure area with a pen, other points or lines to be left unerased may be erased inadvertently.
There is another erasure method in which an erasure area is surrounded by a trace of consecutive input points of a coordinate pointer or a rectangular erasure area is set by a diagonal line interconnecting two input points. With this method, a user first selects an erasure input mode, then designates an erasure area, and erases the area after confirming the erasure area designation. The user is therefore required to perform complicated operations.
Another method (e.g., Japanese Patent Application Laid-open Nos. 63-113720, 3-41572, and 3-171321) in which a width of a line is changed with a detected force of a pen as a coordinate pointer pressed against the input plate, may be applied for using pen input information as the erasure information. With this method, the erasure area size per one input point is changed with a pen pressure. With this method, however, a user is required to have high skill in order to grasp the relationship between a pen pressure and an erasure area size.
An erasure operation is generally performed to erase unnecessary information. It is very inconvenient if the erasure operation requires long time, much labor, high skill, and complicated processes, and the features such as easy-to-use man-machine interface specific to the information processing apparatus are considerably degraded.